Typically, each blade of a turbine wheel comprises an airfoil carried by a platform that is connected to a root by a tang.
The grooves in the disk are regularly spaced apart around the axis of the disk, and between them they define teeth. In the assembled position, the platforms of the blades are spaced a little apart from one another in the circumferential direction and they are spaced apart from the teeth of the disk in the radial direction.
The tangs of the blades are spaced apart from one another in the circumferential direction and between them they define spaces in which damping members are mounted for the purpose of dissipating the energy of the vibration to which the blades are subjected in operation, dissipation being by rubbing against the platforms (EP-A1-0 062 558).
In simple and inexpensive manner, these members are constituted by metal sheets and they also provide radial sealing between the platforms of the blades by bearing radially against the radially internal faces of the platforms.
The blades are held axially in the grooves of the disk by means of annular end plates that are mounted on the disk respectively upstream and downstream, and they bear axially via their peripheries against the blade roots.
In operation, ventilation and cooling air flows from upstream to downstream over the teeth of the disk.
Proposals have already been made to use some of this flow of ventilation air for cooling the blade platforms, which platforms are subjected to high temperatures in operation. One solution consists in providing circuits for passing cooling air in the sealing members that are formed by blocks of relatively thick material. The air that passes along the circuits serves to impact against the internal faces of the platforms (see for example EP-A2-2 110 515).
Nevertheless, that solution is not satisfactory since the above-mentioned circuits are difficult to make and they increase the cost of fabricating the members and also their weight.